adu creates a database containing disk usage statistics of a given
directory. It allows to query that database to quickly retrieve usage
patterns of subdirectories containing files owned by a given user.
Four different output modes are available: global list, global summary,
user list, user summary. The format of the output may be customized
via format strings.
There's an interactive mode which allows to quickly launch many queries
on the same database using different modes and different output files.